Filter obstruction signal arrangement for air conditioning apparatus



* m Aug. 17, 1965 w. T. LADUSAW @ZQLW FILTER DESTRUCTION SIGNALARRANGEMENT FOR AIR CONDITIONING AIFPARATUS Filed Dec. 22, 1961 g \8 ISZNVENTOR.

LADU 5 AW United States Patent 3,201,772 FILTER OBSTRUUTIGN SIGNALARRANGEMENT FUR AIR CONDKTIUNING AIPARATUS William T. Ladusaw,Jeffersontown, Ky., assignor to genleral Electric Company, a corporationof New Filed Dec. 22, 1961, Ser. No. 161,479 1 Claim. (Cl. 349-239) Thepresent invention relates to air conditioning apparatus and moreparticularly to an arrangement in such apparatus adapted to provide asignal when the filter of such apparatus has become dirty and requirescleaning or replacing.

Most air conditioning devices, such as'refrigeration cooling apparatusand warm air furnaces, operate much more efficiently when the airflowing into the particular device is filtered prior to entering theconditioning section of the device. Thus, in room air conditioning unitsor window mounted air conditioners, a filter is usually disposed on theupstream side of the evaporator or cooling unit of the apparatus. Thesame is usually also true in a furnace or central air conditioningapparatus.

It is well known that, when the filter of such a conditioning devicebecomes clogged with particles captured from the air stream, it beginsto reduce the amount of air flow therethrough. In some cases the amountof air flow is reduced to such a point that it seriously hinders theefficient operation of the conditioning device and may possibly bedeleterious to the operation of the device. For example, it is knownthat when the air flow over the evaporator of a window cooler isobstructed too greatly, the temperature of the evaporator drops to apoint where it is likely to cause frost to build up there on. In warmair heating apparatus, when the filter becomes clogged or obstructed,the reduced air flow through the heating apparatus is generally notsufficient to satisfy room temperature conditions called for by the roomthermostat and this results in frequent cycling of the heating apparatuson and off and results in a great waste of fuel the heat of which cannotbe usefully applied to heating air.

It is therefore desirable to provide a filter arrangement in an airconditioning apparatus which will provide some signal to the operatorindicative of the fact that the filter has become obstructed or dirtyand should be cleaned or replaced.

Accordingly, it is an object of the present invention to provide an airconditioning apparatus having an improved signalling arrangement adaptedto indicate when the filter has been too greatly obstructed foreificient operation of the apparatus.

Another object of the present invention is to provide in an airconditioning apparatus an improved signalling arrangement adapted totake advantage of the resistance in the obstructed filter to air fiowtherethrough for actuating the signalling means.

Further objects and advantages of the invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaim annexed to and forming a part of this specification.

In carrying out the objects of the present invention there is providedan air conditioning apparatus for an enclosure comprising a case havinginlet and outlet openings through which enclosure air is circulatedthrough the case. A filter is provided within the case and supportedacross the air stream circulating through the case. The filter supportmeans is so constructed and arranged as to apply a force on the filteronly around the peripheral edges thereof in order to present only alateral frictional 32%,??? Pet-tented 17, 1%65 force holding the filteragainst the force of the air stream flowing through the filter therebyto permit the filter to move from its support means when the resistanceto air flow through the filter due to obstruction of the filter byparticles captured from the air stream becomes greater than thefrictional force of the support means. A weight responsive device isprovided on the downstream side of the filter which receives the weightof the filter when the filter moves from its support means and actuatesan indicating means calling attention to the operator of the apparatusthat the filter has become obstructed by particles and needs cleaning orreplacing.

For a better understanding of the invention, reference may be had to theaccompanying drawings in which:

FIGURE 1 is a schematic elevational view of an air conditioningapparatus having the filter mounting arrangement of the presentinvention;

FIGURE 2 is a partial front view of the air conditioner of FIGURE 1showing the signal indicator slot with the indicator in its normalposition;

FIGURE 3 is an enlarged perspective view of a weight responsive meansfor actuating the signalling device; and

FIGURE 4 is another embodiment illustrating a weight responsivearrangement for energizing an electrical circuit having a signal lighton the front of the air conditioner.

In FIGURE 1 of the drawing there is shown an air conditioning unit ofthe type generally known as a window mounted conditioner or room airconditioner and which is adapted for mounting in an outer wall of anenclosure. While, it is to be understood that the present invention maybe applied to central air conditioning apparatus or furnace arrangementsin which the filter is mounted in a duct work or plenum chamber upstreamfrom the conditioning unit, the invention is shown and described hereinas applied to a room air conditioner where its use is particularly welladapted. The room air conditioner includes a casing or housing 2 adaptedfor mounting in the well-known manner in an outer wall of an enclosure.The casing 2 is divided by a barrier member 3 into two separatecompartments designated the condenser or outer compartment 4 and theevaporator or inner compartment 6. A condenser 7 is positioned in theupper extremities of the condenser compartment 4 and an evaporator orcooling unit 8 is located within the upper region of the evaporatorcompartment 6. The evaporator 8 and condenser 7 are connected inrefrigerant flow relationship with a compressor (not shown) which isusually located in the condenser compartment 4.

In order to circulate an air stream from within the enclosure throughthe evaporator of compartment 6 for cooling the air, there is provided afan or air moving means 11 mounted in the lower portion of theevaporator compartment and upstream from the evaporator. The fan isdriven by a shaft 12 from a motor 13 mounted in the barrier member 3.Air from the room or enclosure to be conditioned is drawn through theinlet opening 14 by the fan 11 and circulated upwardly over theevaporator 8, and then discharged out the front of the case 2 throughthe outlet opening 15. An outdoor air stream is drawn into the condensercompartment 4 through the inlet opening 17 in the outer portion of thecase and circulated upwardly through the compartment 4 over thecondenser 7 and then discharged from the case through the outlet opening18. As indicated in FIGURE 1, both of the fans 11 and 16 are powered bythe same driving means or motor 13 through a common shaft 12 extendingthrough the motor.

As may be seen in FIGURE-S 1 and 2, the front of the air conditioner isusually provided with a decorative front grille, generally designated bythe reference numeral 15.

. The front grille normally contains inlet and outlet grille- Work, suchas that illustrated in FIGURE 1 and designed to permit air flowtherethrough but to prevent foreign objects from entering the evaporatorcompartment. The front, grille extends completely across the front ofthe evaporator compartment 6 and is usually made removable in order topermit periodical access to the evaporator compartment for maintenancepurposes or for removing and replacing the filter arranged therein.

In order to remove particles from the air circulating through evaporatorcompartment 6, a filter 211i is disposed a short distance behindtheinlet opening 14. The filter 21 is arranged entirely across theopening or scroll 22 leading to the fan ill such that any air circulatedthrough the scroll 22 into the fan must previously pass through thefilter 21. Thisfilter may be any of the well known types now on themarketso long as it is substantially rigid in structure so that it maysupport itself on its mounting structure. The filter of the presentembodiment is provided with an outer peripheral frame which rigidlysupports thefiltering material across the inlet opening 14. The filtermaterial may be formed of any of the well known filtering materials suchas foamed plastic, fiberglass, which may be each secured to the frame inany manner well known in the filter art.

Means are provided in the front of the case 2 for mounting the filter 21above the bottom of the case 2. As may best be seen in FIGURE 3, thesemeans include a supporting'bracket or panel 23 extending upwardly fromthe bottom of the case 2 and dispose substantially across the front ofthe unit behind the opening 14. Adjustably positioned on the mountingbracket 23 is a spring support means, which in the illustratedembodiment, comprises at least one and preferably two or more leafspring members 24 having slotted openings 26 therein for attaching thespring members to the support panel 23. The leaf spring member ld may bevertically adjusted with respect to the panel 23 merely by loosening thewing nuts 27, raising or lowering the spring member and again tighteningthe wing nuts. The lower end of the filter Zlla rests on the springsupport 24 directly behind the panel 23. The upper end of the filter 21bis adapted to fit through the opening 14 (seen only in FIGURE 1) andWithin the channel formed between the retaining members 25 and 25aextending downwardly from the structure supporting the evaporator 8.Downwardly extending support 25 is best arranged at an angle withrespect to the plane of the filter in order to permit the filter to beloosely retained at its upper end 2112 thereof. The spring means orspring member 24 exerts a force upwardly along theplane of the filterbut, as will be noted in FIGURE 1, there is nothing to prevent thefilter 21 from being pulled inwardlytoward the fan 1]. when theresistance to air flow through the filter becomes great enough toovercome the lateral frictional force exerted on the peripheral edge ofthe filter by the spring means 24; Thus, while a force is exerted ontheouter pe'ripheraledge of the filter in the plane of'the filter, thereis :very little force other than the lateral frictional force exertedbythe spring means 24 for preventing the'filterfrom being pulledinwardly by the force of the air stream on the'filter as it flows towardthe fan 11.

It should be mentioned that the spring support member or members 24 maybe adjusted by means of a wing nut 27 and the slot 26 to provide varyingamounts of pressure in the plane of the'filter 21. However, it isdesirable that the bottom edge of the slot 26 how disposed as to preventthe spring catch 24'from being'moved into a position to exert so great apressure as to prevent the filter 21 from being moved from its mountingmeans even though the filter becomes greatly obstructed by particles.Thus, when the resistance to air fiow through the filter overcomes thelateral frictional force exerted by the spring members 2 the filter 21is moved inwardly away from vertical supporting means.

A space 28 is provided on the downstream side of the filter 21 which isadapted to receive the filter as it moves from its mounting support.Within the space 23 in the lower portion of the case 2 is provided aweight responsive means adapted to actuate an indicator device on thefront of the case whenever the filter 21 falls into the space 28. Morespecifically, as may be seen in FIGURES 1 and 3, there is provided apivot bar 2% which is mounted through a hole 23a formed in the supportpanel 23 and supported by a bracket 36 and pivot pin 30a. Bracket 3d issuitably attached to the panel 23 by welding or other means well knownin the art. One lever arm 29a of the bar 29 extends into the space 28beneath the filter 21 and the opposite or front lever arm 2% extendstoward the front of the caseZ. Attached to the front end of the leverarm 2% is an indicia carrying plate or means 31 which may be movedupwardly or' do wnwardly with respect to the front of the case or withrespect to the front grille'19. As may be seen in FIG- URES 1 and 2, thefront of the case is provided with a slot 32 through which may be seenindicia on the plate 31. The pivot arm '29 in its normal position isweighted on the pivot or lever arm 2% so that the pivot bar 29 isnormally disposed as in FIGURE 1 with the lever arm 29a pivoted up andthe lever arm 29bpivoted down. As may be seen in FIGURE 1, when the armis in its normal position the indicia received through the slot 32 onthe 'front of the unit indicates that the filter is clean. However, whenthe filter 21 is moved from its mounting support, it drops into thespace 28 onto the arm 29a and pivots the front end or lever arm 291')upwardly with respect to the slot 32 on the front of the case. Wheneverthe filter 21 moves the arm 29a to the downward position, shown indotted lines in FIGURE 1, the indicia on the plate 31 discloses that thefilter is dirty. This will be apparent from the front view of the slot32 and plate 31 as indicated in FIGURE 2.

In order to prevent the filter '21 from being drawn into the fan 11 asit is moved from its filter supporting means, a plurality of uprightbars 33 are provided on the upstream side of the fan 11. Upright bars33' extend across the region or space 28 and hold the filter out of thescroll 22 thereby preventing the filter from in any way encountering the'fan '11. Obviously bars of other configuration or other means such as awire screen extending across the opening in this region could be usedfor this same purpose.

Referring now'to FIGURE 4 there is shown a second embodiment of thepresent invention in which the filter 21 is adapted to be removed fromits supporting means in substantially the same manner as dGSCllbCd-Wlthrespect to' the above arrangement; In this arrangement, however, theweight responsive means for actuating the indlcating means on the frontof the unit is a weight responsive switch means generally designated bythe reference numeral 36. The switch means comprises spring loadedswitch'arrn 38 which may be depressed by the weight of the filter 21 inthe manner shown in FIGURE 4. In its normal.position'thespring loadedswitch arm 38 is moved upwardly away from'the switch box 3'7 so that theweight responsive switch 36 is not completed through an electricalcircuit including conductor lines 39 and 39a leading to a signal orindicator light 41 in a socket .42 mounted in'the front of the case. Thelight 41 is connected in series across the power supply by means of theWeight responsive switch'36 which completes the circuit from a source ofelectrical power connectirig With'the switch box 37 when the weight ofthe filter ll depresses the spring loaded switch arm 38 as shownin'FIGURE 4. A plastic or glass cover 43 may be provided over the light41 to provide a pleasing appear- .ance through an opening 44 in thefront grille'19 to provide a signal when the filter 21 has moved fromthe mounting support. The glass or plastic cover 43.also serves toprotectthelight 411. Itwill beunderstood that a light is not the onlymeans which may be energized when the electrical circuit, including theweight responsive switch 36, is energized. For example, a bell could beenergized by the circuit thereby providing a warning to the operator ofthe apparatus that the filter is dirty and should be replaced.

While in accordance with the patent statutes there has been describedwhat at present is considered to be the preferred embodiments of theinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made therein without departing from theinvention, and it is, therefore, the aim of the appended claim to coverall such changes and modifications as fall within the true spirit andscope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

An air conditioning apparatus for an enclosure comprising a case, airinlet and outlet openings in said case through which enclosure air iscirculated through said case, air moving means mounted in said case forcirculating a stream of enclosure air through said case, a filter,support means in said case for supporting said filter in a substantiallyvertical position across said air stream circulating through said case,said support means comprising means for retaining the upper edge of saidfilter against horizontal movement from said support means adjustablespring members engaging the outer periphery of said filter to apply aforce on said filter substantially along the plane thereof therebypresenting only a lateral frictional force against the force of said airstream flowing through said filter so that the bottom edge of saidfilter may move from said support means when the resistance to air flowthrough said filter due to obstruction of said filter by particlescaptured from said air stream becomes greater than said frictional forceof said support means, an open space on the downstream side of saidfilter adapted to receive said filter as it moves from said supportmeans, a weight responsive device in said open space adapted to receivethe weight of said filter when said filter moves from said support meansinto said space, an indicating means actuated by said weight responsivedevice for signalling when said filter has moved from said support meansthereby calling attention to the operator of the apparatus that saidfilter has become obstructed by particles.

References fitted by the Examiner UNITED STATES PATENTS NEIL C. READ,Primary Examiner.

